Recent studies show that gastrointestinal hormones/growth factors may stimulate cell growth by stimulating multiple intracellular tyrosine phosphorylation (TyrP) signaling cascades. However at present little is known about the ability of many gastrointestinal hormones/growth factors to activate these cascades in GI tissues. Our studies have been in two general areas, which include studies of intracellular signaling cascades primarily by tyrosine kinases and studies of tumoral growth attempting to develop novel agents for growth inhibition. Recent studies show that gastrointestinal hormones, similar to growth factors, may stimulate cell growth/cell signaling by stimulating multiple intracellular tyrosine phosphorylation (TyrP) cascades. Whereas these cascades have been extensively investigated with growth factors, little is known in this area with may gastrointestinal hormones. The goal of these studies is to clarify this area primarily concentrating on cholecystokinin receptor cascades and bombesin receptor activation using primarily pancreatic acini as a model natural cell system. Studies involving phosphorylation of PKD1, GAB1, AKT have been completed and studies of PKC theta are in process. Novel cytotoxic agents coupled to different GI hormones have been described.